function [ Fgrid, Fgrid_b ] = Bivariate_4point( grid , omega, iter )
%-----------------------------------------------------------------
% Input:
% grid(m,n) - a grid over Z^2
% omega - tension parameter
% iter - # of iteration needed
% Output:
% Fgrid(2^(iter+1)*m-5(1+2+4+...+2^iter),2^(iter+1)*m-5(1+2+4+...+2^iter))
%-----------------------------------------------------------------
% ABSTRACT
% Tensor product. the middle point is insert in the order y->x of
% calculation
%-----------------------------------------------------------------
% NIr Sharon, 07-05-12
%-----------------------------------------------------------------
Fgrid = grid;
Fgrid_b = grid;
for i=1:iter
   Fgrid = Bivariate_4pointRefinement( Fgrid , omega );
   Fgrid_b = Bivariate_4pointRefinement_boundary( Fgrid_b , omega );
end


end

